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chan_pjsip: Fix deadlock when masquerading PJSIP channels.

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Performing a directed call pickup resulted in a deadlock when PJSIP
channels were involved.

A masquerade needs to hold onto the channel locks while it swaps channel
information between the two channels involved in the masquerade.  With
PJSIP channels, the fixup routine needed to push a fixup task onto the
PJSIP channel's serializer.  Unfortunately, if the serializer was also
processing a task that needed to lock the channel, you get deadlock.

* Added a new control frame that is used to notify the channels that a
masquerade is about to start and when it has completed.

* Added the ability to query taskprocessors if the current thread is the
taskprocessor thread.

* Added the ability to suspend/unsuspend the PJSIP serializer thread so a
masquerade could fixup the PJSIP channel without using the serializer.

ASTERISK-24356 #close
Reported by: rmudgett

Review: https://reviewboard.asterisk.org/r/4034/
........

Merged revisions 424471 from http://svn.asterisk.org/svn/asterisk/branches/12
........

Merged revisions 424472 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@424473 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2014-10-03 17:47:42 +00:00
parent 4967478d18
commit 0165c5f95a
18 changed files with 253 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
main/taskprocessor.c
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@@ -78,9 +78,9 @@ struct ast_taskprocessor {
long tps_queue_size;
/*! \brief Taskprocessor queue */
AST_LIST_HEAD_NOLOCK(tps_queue, tps_task) tps_queue;
/*! \brief Taskprocessor singleton list entry */
AST_LIST_ENTRY(ast_taskprocessor) list;
struct ast_taskprocessor_listener *listener;
/*! Current thread executing the tasks */
pthread_t thread;
/*! Indicates if the taskprocessor is currently executing a task */
unsigned int executing:1;
};
@@ -600,6 +600,8 @@ static struct ast_taskprocessor *__allocate_taskprocessor(const char *name, stru
ao2_ref(listener, +1);
p->listener = listener;
p->thread = AST_PTHREADT_NULL;
ao2_ref(p, +1);
listener->tps = p;
@@ -752,6 +754,7 @@ int ast_taskprocessor_execute(struct ast_taskprocessor *tps)
return 0;
}
tps->thread = pthread_self();
tps->executing = 1;
if (t->wants_local) {
@@ -768,6 +771,7 @@ int ast_taskprocessor_execute(struct ast_taskprocessor *tps)
tps_task_free(t);
ao2_lock(tps);
tps->thread = AST_PTHREADT_NULL;
/* We need to check size in the same critical section where we reset the
* executing bit. Avoids a race condition where a task is pushed right
* after we pop an empty stack.
@@ -789,3 +793,13 @@ int ast_taskprocessor_execute(struct ast_taskprocessor *tps)
}
return size > 0;
}
int ast_taskprocessor_is_task(struct ast_taskprocessor *tps)
{
int is_task;
ao2_lock(tps);
is_task = pthread_equal(tps->thread, pthread_self());
ao2_unlock(tps);
return is_task;
}